Data reading machine



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DATA READING MACHINE Filed July 6, 1954 18 Sheets-Sheet 14 Sept. 29,1959 P. F. SMITH DATA READING MACHINE 18 Sheets-Sheva?l 15 Filed July 6.1954 MMA VVV Sept. 29, 1959 P. F. SMITH DATA READING MACHINE 18Sheets-Sheet 16 Filed July 6, 1954 Sept. 29, 1959 P. F. SMITH DATAREADING MACHINE 18 Sheets-Sheet 1'7 Filed July 6, 1954 Sept. 29, 1959 P.F. SMITH DATA READING MACHINE 18 Sheets-Sheet 18 Filed July 6. 1954 m Em ||H H H H LLI llllllllllllllll I1 I QR! .I llllllllllll ILL zLCfLH |1-2 -imrf lllllllllllllllllllllllllllllll mf. mm1 1| www Patented Sept.29, 1959 iii? ce DATA READING MACHINE Perrin F. Smith, Santa ClaraCounty, Calif., assignor to International Business Machines Corporation,New York, NX., a corporation of New York Application `uly 6, *1954,Serial No. 441,237 14 Claims. (Cl. 178--17) The present inventionapertains generally to data reading machines, and more particularly itrelates to data reading machines utilizing a ilying spot scanningsystem.

It is an object of this invention to provide an improved data readingmachine which is capable of reading information at a very high rate ofspeed.

Another object is to provide a groping reader, i.e., a reader which isadapted to look for, locate and read information from a document.

A further object is to provide a reader employing a :flying spotscanning system arranged to scan -only those portions of a document uponwhich information is stored.

Still another object is to provide a reader of the type described whichis controlled first to scan a portion of a document to sense thepresence of a line of characters, second to scan a line of characters sosensed, and third to scan each character in a sensed line to determineits identity.

A still further object is to provide a novel means for skew correction.

Another object is to provide a reader not adversely affected by moderateskew of a document to be read.

Still another object is to provide a reader adapted to scan a line ofcharacters and arranged to correct for skew, if necessary, at eachcharacter in a line.

A further object is to provide a reader arranged to grope for charactersto be read whereby the dimensional characteristics of the document needbe relatively stable only over the small area upon which a character isrecorded.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode which has been contemplated of applying that principle.

In the drawings:

l Fig. 1 is a block diagram of the reader of the invention.

Fig. 2 is an illustration of a document capable of being read by thenovel reader.

Fig. 3 is a diagrammatic illustration of a read cycle.

Fig. 4 is a suggested code for utilization with the reader.

Figs. 5a and 5b comprise a schematic diagram of the vertical sweepcircuit.

Fig. 6 is a schematic diagram of the pulse shaper.

Fig. 7 is a schematic diagram of the horizontal sweep circuit.

Figs. 8a, 8b and 8c comprise a schematic diagram of the shift registerutilized herein.

Figs. 9a, 9b, and 9c comprise a schematic diagram of the read cyclegenerator.

Fig. l0 is a schematic diagram of the detector.

Fig. 11 is a schematic diagram of the horizontal jizzle generator.

Fig. 12 is a schematic diagram of the print-out delay circuit. Y

Fig. 13 is a schematic diagram of the vertical iizzle generator.

Fig. 14 is a schematic diagram of theskew corrector circuit.

Fig. 15 is a schematic diagram of the print-out delay matrix.

Fig. 16 shows the relationship of several pulse trains to be describedin connection with the skew corrector circuit.

The present invention comprises a flying spot scanning system arrangedto read coded information from a document. The information is stored onthe document either in the form of small punched holes, in which casethe document is read by sensing the light passing through the holes, asillustrated herein, or in the form of printed dots or bars wherein thedocument is read by sensing the reflected light. In any case, theinvention is not directed to the sensing structure and any convenientsensing means may be employed. Generally, the reader of the invention isarranged to Search the face of a document to detect the presence andlocation of information to be read, it being ignorant of both thepresence and the location, until the information is located, and forthis reason the reader is identified as a groping reader.

Referring to Fig. 2, a document 25 capable of being read by the novelreader is illustrated. The code utilized herein to identify charactersis contained within twocolumns (Fig. 3) having a total of four holepositions in each column. The lower left-hand hole 26 in each columnset, indicated as position I, is referred to as the key hole and is usedto signify the presence of a coded character. Six of the remaining sevenhole positions, i.e., positions II, III, IV, VI, VII and VIII, providethe bits of a six-bit binary code for character identification, theremaining hole position, position V, being suitable, for example, forproviding a self-checking code system, as is well known. A suggestedcode for utilization herewith is shown in Fig. 4.

It will be noted that to the left of each line of coded information onthe document shown in Fig. 2, in the lefthand margin thereof, there isprovided a rectangular hole 27, the holes 27 being referred tohereinafter as start holes. Each start hole, therefore, signifies thepresence of a line of coded characters. A document 25 (Fig. 1) to beread is disposed in any convenient manner between the face of a cathoderay tube 28 and a photocell 29, suitable condensing lenses 31 and 32being provided between the tube and the document and between thedocument and the photocell, respectively, and it will be obvious tothose familiar with ying spot scanning systems that the cathode ray beammay be controlled to focus the light emanating from the beam on variousselected portions of the document. Additionally, it will be observedthat, when the spot of light is focused upon a hole in the document, thephotocell 29 will provide an indication thereof.

The ying spot scanning system utilized herein is arranged to irst scanthe document 25 (Fig. l) to locate a start hole 27 (Fig. 2), the cathoderay beam in the present embodiment being controlled to sweep theleft-hand margin of the document from the top thereof toward the bottomuntil it encounters the irst start hole 27a. At this time, means areprovided to stop the vertical sweep and, in addition, to initiate ahorizontal sweep. The beam is then controlled by the horizontal sweep tomove across the document until it locates the first key hole 26. (Thepath of the cathode ray beam over the document is indicated in phantomlines in Fig. 3.) As noted above, the key hole 26 indicates the presenceof a coded character, and it is when the photocell 29 senses a key holethat the horizontal sweep is discontinued and a read cycle is commencedto determine the identity of the coded character associated with the keyhole. The structure of the invention is at this time arranged to movethe beam sequentially to each of the bit positions, as indicated in Fig.3, to determine presence or absence of a bit at each bit position and tothereby ,determine the identity of the character being read.

Upon completion of a read cycle, fthe horizontal sweep is resumed untilthe next key hole is encountered, at which time the next character isidentified in a similar manner. After a complete line has been read, thebeam is returned to the left-hand margin, to the start hole 27a, and thevertical sweep is resumed to search for the next start hole 27b (Fig.2).

Briefly stated and with reference to Fig. l, this invention provides aying spot which may be generated by a cathode ray tube 28 and whichscans through a data sheet 25 and upon a photocell `29. To initiate ascanning operation, a start switch 3'6 is closed, whereupon a deflectionwave is generated by a vertical sweep circuit, is passed by a verticaljizzle and adder circuit and Vby a vertical deflection amplifier to anelectron beam deecting means associated with the cathode ray tube 28.The flying spot is thus caused to vscan downwardly until it passesthrough a start hole associated with a horizontal line on the data sheet25 and is sensed by the photocell 29. A voltage thus generated by thephotocell 29 is ampliied and is impressed upon the vertical sweepcircuit to halt the downward scanning of the spot. The voltage isfurther impressed upon a pulse shaper and thence passes to a horizontalsweep circuit that generates a -second deflection wave which is passedby the horizontal .jizzle and adder circuit and by the horizontaldeflection amplifier to a further deflection means associated with theC.R.T. 28. The spot is thus caused to scan horizontally across the datasheet 25 until a key hole associated with a character is sensed,whereupon a signal from the photocell 29 is amplified and passed by thepulse shaper to a read cycle generator and to the horizontal sweepcircuit. A readcycle is thus initiated during which the read cyclegenerator passes a sequence of signals to the vertical and horizontaljizzle and adder circuits and through the vertical and horizontaldeflection amplifiers to move the spot incrementally through apredetermined read pattern for sensing bits which may be detected andpassed into a shift register. At the end of the read cycle, the bitsrecorded in the shift register are passed to a relay decoding tree fordetermining the character which is thence printed by an electricVtypewriter. After a delay period to permit printing, the beam willcontinue the horizontal scanning with interruptions for further readcycles when other key holes are sensed, and at the end of the scannedline, it will retrace 'to the left and continue the vertical scanningwith Vinterruptions -for further horizontal scans when other start holesare sensed. A jizzle or high frequency oscillation of the flying spot isintroduced by the jizzle and adder circuits to effectively broaden theflying spot, thereby minimizing the possibility that a start hole or akey hole Vwill be missed and bypassed as the data sheet 25 is scanned. Avertical skew corrector provides a correction voltage for verticaldeflection, the correction voltage being equal to the instantaneousjizzle voltage when a key hole is sensed.

Vertical sweep The novel reader of the invention is illustrated in blockform in Fig. l, and it will be noted that a manual start key 36 isprovided to start the beam groping vertically for start holes 27. Oncestarted, however, the reader continues on its own until the completedocument has been-read. Although a manual start and a typewriter outputhave been shown, it will be understood that the invention is not limitedthereby and that Vthese have been shown for illustrative purposes only.Actually, the reader is much more suited soV some form of electronicprint-out since it is extremely'fast as compared with the typewriters oftoday.

Thev start key 36 (Fig. 5a) is arranged to connect +150 volts to thecontrol grid 37 of a tube 38, the tube 38, a tube 39 and the circuitryassociated therewith comprising a Schmitt trigger 35. The tube 38 isnormally cut olf, the tube 39 being arranged normally to conduct. When,however, the potential of the grid 37 is raised by actuation of thestart key 36, the tube 38 is rendered conducting, the tube 39is cut olf,and the plate `40 thereof rises in potential. When the key 36 isreopened, to remove the positive potential from lthe grid 37 of the tube36,V

the plate 40 of the tube 39 drops in potential since that tube againconducts. The plate `40 is coupled through a diode 42 to one controlgrid 43 of a bistable trigger 44 comprising vacuum tubes 45 and 46. Thetrigger 44 has two stable conditions, one being when the tube 45 isconducting and the tube `46 is cut off, and the other when the tube 45is cut off andthe tube 46 is conducting. Throughout this description allsuch bistable triggers will be referred to as on when :the left-handtube, as viewed in the drawings, is conducting, and as o when theopposite condition exists. In the instant case, the trigger 44 isassumed to be on, initially. When the plate 40V of the tube 39 drops inpotential, the resulting negative impulse taken therefrom is appliedthrough the diode 42 to the control grid 43, thereby cutting off thetube 45 and causing the trigger 44 to switch off. At this time the plate.potential of the tube 46 drops.

The plate 47 is connected to the control grid 43 of an inverter tube 49,the plate 5i. of which is connected by a line 50 to the cntrol grid 52(Fig. 5b) of a cathode follower 53. When the trigger 44 (Fig. 5a) is on,the inverter is biased to conduct and the cathode of the cathodefollower 53 is therefore normally slightly below ground potential. When,however, the plate 47 of the tube 46 drops in potential, due to thetrigger 44 being switched off, the inverter tube 49 is cut off andremains cut off until the trigger 44 is again turned on. As soon as theinverter 49 is cut off, its plate 5l rises in potential sufficiently toraise the potential of the cathode of the cathode follower 53 (Fig. 5b)well above ground potential. Thus, it will now be clear that, when ythekey 36 is depressed and released, the potential of the grid 52, and thusof the cathode 54 of the cathode follower 53, goes up. Additionally,when the trigger 44 is again turned on, thereby rendering the tube 45conductive and the tube 46 cut off, the cathode 54 of the cathodefollower 53 drops back to slightly below ground potential.

One side of a condenser 56 is connected through a diode 57 and aresistor 58 to the cathode 54 of the cathode follower-53, the other'side thereof being connected to ground, Vand it will be noted that,when the cathode 54 is above ground potential, the condenser 56 chargesthrough the diode 57. The non-grounded side of the condenser 56 isadditionally connected to the grid 59 of a tube 6l, the plate 62 ofwhich is connected to the grid 63 of a cathode follower 64. Connectingthe cathode 65 of the cathode follower 64 to one end of a resistor 66(Fig. 13) is a line 67. .TheV resistor y66 forms a portion of thevertical adder for controlling the potential of the vertical deflectionplates of the cathode ray tube. Thus, when the cathode 54 (Fig. 5b) ofthe cathode follower 53 goes up, the condenser 56 charges, raising thepotential of the grid 59 of the tube 61 and lowering the potential ofthe plate 62 thereof, lowering the potential of the grid 63 and cathode65 of the cathode follower 64, thereby lowering thepotential added intothe vertical deflection system through the adding resistor 66 (Fig. 13)and causing the cathode ray beam to sweep downwardly across `thedocument 25. It should now be clear that the vertical sweep circuitmoves the cathode ray beam downwardly as long as the trigger 44 (Fig.5a) is off since, while the trigger 44 is off, the cathode potential ofthe cathode follower 64 (Fig. 5b) drops exponentially.

Also connected to the non-grounded side of the condenser n56 is theplate 68 of a dunking triode 69, the

